One type of glass sheet forming as disclosed by U.S. Pat. No. 4,578,103 Fackleman; U.S. Pat. No. 4,615,724 Fackleman; U.S. Pat. No. 5,002,599 McMaster et al.; and U.S. Pat. No. 5,004,491 McMaster et al. involves releasing a heated glass sheet from a topside transfer platen onto a mold for forming. With this type of forming in order to have the minimum drop distance, the orientation of the glass sheet on the mold is controlled by the orientation of the downwardly facing topside transfer platen which is conventionally inclined to receive the glass sheet from a heating conveyor. Thus, the continued processing of the glass sheet on the mold is controlled by the orientation of the mold upon release, and this orientation controls the orientation of the processing throughout the entire forming process even upon eventual cooling when it may be desirable to have a different orientation to permit location of the formed glass sheet between closely spaced quench units of a cooling station.
Accurate forming of heated glass sheets requires that the molds utilized to perform the forming be properly located despite the thermal expansion that takes place when the system involved is heated to a glass forming temperature. One way in which proper positioning of molds has previously been provided is by readjusting the mold position during each cycle through alignment devices such as disclosed by U.S. Pat. No. 5,092,916 McMaster. Another way in which mold positioning has been achieved is by use of positioning devices including sinter-bonded fused silica positioners that have a very low rate of thermal expansion so as to thereby maintain proper positioning of locators that provide the mold positioning such as disclosed by U.S. Pat. No. 5,230,728 McMaster.